Dryer circuit 4-wire question

I am wiring a dryer circuit with a 10-3 wire running out to the main service disconnect panel. The plug at the wall end is a typical 4-plug receptacle. My question is, at the service panel there are additional slots for breakers, a grounding bar, but no neutral bus bar. There is only a grounding bus bar that is bonded to the neutral wire.

I have hooked up the red and black wire to the two poles on the 30 amp breaker and the white and ground wire to the grounding bus.

My problem is that there is only power to one of the hot wires at the dryer receptacle. The red has power, but the black does not.

What am I missing here??? I know there should be a neutral grounding bus, but at the main service disconnect panel there isn't.

Dryer circuit 4-wire question

Nope, it's 4 breakers. I believe it's 4 single pole breakers, but I'm not at my house at the moment to check.

It's brand new construction. My electrician bailed, so I'm trying to troubleshoot. I have basic electrical experience, but nothing dealing with main panels/service disconnect

well, you have a problem with your mains then. While you can have up to 6 breakers as a main disconnect, you still need 2 pole breakers to disconnect both hot legs simultaneously.

and since this is brand new, it is not a split bus. If this is the only panel in the building, you have a problem happening in that panel.
when you get a chance, check it out because it definitely does not sound right.